/****************************************************************************
 *
 * Copyright 2017 Samsung Electronics All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 *
 ****************************************************************************/
/****************************************************************************
 * drivers/bch/bchdev_driver.c
 *
 *   Copyright (C) 2008-2009, 2014-2016 Gregory Nutt. All rights reserved.
 *   Author: Gregory Nutt <gnutt@nuttx.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/
#include <tinyara/config.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>

#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <tinyara/fs/fs.h>
#include <tinyara/fs/ioctl.h>

#include "bch.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Private Function Prototypes
 ****************************************************************************/
static int     bch_open(FAR struct file *filep);
static int     bch_close(FAR struct file *filep);
static off_t   bch_seek(FAR struct file *filep, off_t offset, int whence);
static ssize_t bch_read(FAR struct file *filep, FAR char *buffer,
						size_t buflen);
static ssize_t bch_write(FAR struct file *filep, FAR const char *buffer,
						 size_t buflen);
static int     bch_ioctl(FAR struct file *filep, int cmd,
						 unsigned long arg);
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int     bch_unlink(FAR struct inode *inode);
#endif

/****************************************************************************
 * Public Data
 ****************************************************************************/
const struct file_operations bch_fops = {
	bch_open,	/* open */
	bch_close,	/* close */
	bch_read,	/* read */
	bch_write,	/* write */
	bch_seek,	/* seek */
	bch_ioctl,	/* ioctl */
#ifndef CONFIG_DISABLE_POLL
	0,			/* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
	bch_unlink,	/* unlink */
#endif
};

/****************************************************************************
 * Private Functions
 ****************************************************************************/
/****************************************************************************
 * Name: bch_open
 *
 * Description: Open the block device
 *
 ****************************************************************************/
static int bch_open(FAR struct file *filep)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	/* Increment the reference count */

	bchlib_semtake(bch);
	if (bch->refs == MAX_OPENCNT) {
		return -EMFILE;
	} else {
		bch->refs++;
	}

	bchlib_semgive(bch);
	return OK;
}

/****************************************************************************
 * Name: bch_close
 *
 * Description: close the block device
 *
 ****************************************************************************/
static int bch_close(FAR struct file *filep)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;
	int ret = OK;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	/* Flush any dirty pages remaining in the cache */
	bchlib_semtake(bch);
	(void)bchlib_flushsector(bch);

	/*
	 * Decrement the reference count (I don't use bchlib_decref() because I
	 * want the entire close operation to be atomic wrt other driver
	 * operations.
	 */
	if (bch->refs == 0) {
		ret = -EIO;
	} else {
		bch->refs--;

		/*
		 * If the reference count decremented to zero AND if the character
		 * driver has been unlinked, then teardown the BCH device now.
		 */
		if (bch->refs == 0 && bch->unlinked) {
			/* Tear the driver down now. */
			ret = bchlib_teardown((FAR void *)bch);

			/*
			 * bchlib_teardown() would only fail if there are outstanding
			 * references on the device.  Since we know that is not true, it
			 * should not fail at all.
			 */
			DEBUGASSERT(ret >= 0);
			if (ret >= 0) {
				/* Return without releasing the stale semaphore */
				return OK;
			}
		}
	}

	bchlib_semgive(bch);
	return ret;
}

/****************************************************************************
 * Name: bch_seek
 ****************************************************************************/
static off_t bch_seek(FAR struct file *filep, off_t offset, int whence)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;
	off_t newpos;
	int ret;

	DEBUGASSERT(inode && inode->i_private);

	bch = (FAR struct bchlib_s *)inode->i_private;
	bchlib_semtake(bch);

	/* Determine the new, requested file position */
	switch (whence) {
	case SEEK_CUR:
		newpos = filep->f_pos + offset;
		break;

	case SEEK_SET:
		newpos = offset;
		break;

	case SEEK_END:
		newpos = bch->sectsize * bch->nsectors + offset;
		break;

	default:
		/* Return EINVAL if the whence argument is invalid */
		bchlib_semgive(bch);
		return -EINVAL;
	}

	/*
	 * Opengroup.org:
	 *
	 *  "The lseek() function shall allow the file offset to be set beyond the
	 *  end of the existing data in the file. If data is later written at this
	 *  point, subsequent reads of data in the gap shall return bytes with the
	 *  value 0 until data is actually written into the gap."
	 *
	 * We can conform to the first part, but not the second. But return EINVAL
	 * if
	 *
	 *  "...the resulting file offset would be negative for a regular file,
	 *  block special file, or directory."
	 */
	if (newpos >= 0) {
		filep->f_pos = newpos;
		ret = newpos;
	} else {
		ret = -EINVAL;
	}

	bchlib_semgive(bch);
	return ret;
}

/****************************************************************************
 * Name: bch_read
 ****************************************************************************/
static ssize_t bch_read(FAR struct file *filep, FAR char *buffer, size_t len)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;
	int ret;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	bchlib_semtake(bch);
	ret = bchlib_read(bch, buffer, filep->f_pos, len);
	if (ret > 0) {
		filep->f_pos += len;
	}

	bchlib_semgive(bch);
	return ret;
}

/****************************************************************************
 * Name:bch_write
 ****************************************************************************/
static ssize_t bch_write(FAR struct file *filep, FAR const char *buffer, size_t len)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;
	int ret = -EACCES;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	if (!bch->readonly) {
		bchlib_semtake(bch);
		ret = bchlib_write(bch, buffer, filep->f_pos, len);
		if (ret > 0) {
			filep->f_pos += len;
		}

		bchlib_semgive(bch);
	}

	return ret;
}

/****************************************************************************
 * Name: bch_ioctl
 *
 * Description: Return device geometry
 *
 ****************************************************************************/
static int bch_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
	FAR struct inode *inode = filep->f_inode;
	FAR struct bchlib_s *bch;
	int ret = -ENOTTY;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	/* Is this a request to get the private data structure */
	if (cmd == DIOC_GETPRIV) {
		FAR struct bchlib_s **bchr = (FAR struct bchlib_s **)((uintptr_t)arg);

		bchlib_semtake(bch);
		if (!bchr || bch->refs == MAX_OPENCNT) {
			ret = -EINVAL;
		} else {
			bch->refs++;
			*bchr = bch;
			ret = OK;
		}

		bchlib_semgive(bch);
	}
#ifdef CONFIG_BCH_ENCRYPTION
	/* Is this a request to set the encryption key? */
	else if (cmd == DIOC_SETKEY) {
			memcpy(bch->key, (FAR void *)arg, CONFIG_BCH_ENCRYPTION_KEY_SIZE);
			ret = OK;
	}
#endif
	/* Otherwise, pass the IOCTL command on to the contained block driver */
	else {
		FAR struct inode *bchinode = bch->inode;

		/* Does the block driver support the ioctl method? */
		if (bchinode->u.i_bops->ioctl != NULL) {
			ret = bchinode->u.i_bops->ioctl(bchinode, cmd, arg);
		}
	}

	return ret;
}

/****************************************************************************
 * Name: bch_unlink
 *
 * Handle unlinking of the BCH device
 *
 ****************************************************************************/
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
static int bch_unlink(FAR struct inode *inode)
{
	FAR struct bchlib_s *bch;
	int ret = OK;

	DEBUGASSERT(inode && inode->i_private);
	bch = (FAR struct bchlib_s *)inode->i_private;

	/* Get exclusive access to the BCH device */
	bchlib_semtake(bch);

	/* Indicate that the driver has been unlinked */
	bch->unlinked = true;

	/*
	 * If there are no open references to the drvier then teardown the BCH
	 * device now.
	 */
	if (bch->refs == 0) {
		/* Tear the driver down now. */
		ret = bchlib_teardown((FAR void *)bch);

		/*
		 * bchlib_teardown() would only fail if there are outstanding
		 * references on the device.  Since we know that is not true, it
		 * should not fail at all.
		 */
		DEBUGASSERT(ret >= 0);
		if (ret >= 0) {
			/* Return without releasing the stale semaphore */
			return OK;
		}
	}

	bchlib_semgive(bch);
	return ret;
}
#endif
